For the understanding of the ocean environments, fundamental characteristics of the flow and diffusions in the ocean are briefly outlined and the seasonal observation data of the ocean structures in Osaka-Bay are introduced. A review on the environmental researches relating to the impact assessment of a Mega-Float, which were mainly conducted by some groups of the ocean engineering, is given. A project for the ocean fertilization by using an array of vertical wall structures which aims to generate the up-welling tidal current is introduced. An expected role of the ocean and the ocean engineering is expressed to solve the global environmental problems in the near future.

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Recently, the authors proposed a modified κ-ε model, applied it to flat plate boundary layer and stern flow, and improved prediction accuracy of mean flow field with longitudinal vortex. The modified κ-ε model is also applied to turbulent swirling flow in a straight pipe in order to express swirling flow more accurately. The modified κ-ε results are validated through comparisons with experiments, a standard κ-ε results, and a computational results for Nisizima-Yokoi. The conclusion is that the modified κ-ε results show some improvements of tangential velocity W and reduction of axial velocity U near the core region.

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A vehicle based on WIG(Wing In Ground effect)is expected as one of the candidates of future high speed vessels on seaway. In the former part of the present study, Morino's panel method is applied to aerodynamic analyses around a Ram-wing type 3D WIG with special reference to aerodynamic characteristics of its side end plates. Under the consideration of these analyses, aerodynamic shape optimization problems of WIG are discussed in the latter part of this paper. Numerical examples of optimized wing section are shown, in which the optimizations are carried out by means of the aerodynamic analysis based on the panel method and the nonlinear programming technique based on SQP(Sequential Quadratic Programming)

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Presented hull form optimization method based on Rankine source method can represent naval architecture for optimized hull forms such as a 3D geometry data. 3D geometry data is important in the practical design stage, go this method is very convenient as design tool. However, before using this method as the design tool, it is necessary to verify the accuracy and the efficiency of the design tool. In this paper, we experimented and measured the wave resistance of the parent hull form and optimized hull form by using this optimization method, and verified it. From these experimental results, the accuracy and the efficiency of this method are verified.

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There are papers about improvement of the ship performance by the representative ships, for examples, the IDEMITSU-MARU the TOKYO-MARU, etc. There are, however, few papers about ship performance of the whole ships. The data of ship performance were collected since 1963 by SEMPAKUMEISAISHO, which holds all of ships registered in Japan. The first paper showed the results about the crude oil tankers. This paper shows the results about the container ships, namely, change of principal dimensions, sea speed, maximum continuous output and analysis results for ship performance with some assumptions, The results show that the ships, which are recently built, have better performance with lower Fn.

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There are papers about improvement of the ship performance by the representative ships but few papers about ship performance of the whole ships. The first and second reports showed data of ship performance of the crude oil tanker and the container ship respectively, which were collected since 1963 by SEMPAKUMEISAISHO. In this paper, there are some results about the ferry boats, which are collected form the same as the crude oil tankers. They show some changes of principal dimensions and sea speed, the maximum continuous output. It is clear from the analysis result for ship performance that the ferry boats, which are recently built, have not better performance with the year of build than the cases of the crude oil tanker and the container ship. Because the ferry boat is too difficult to be changed larger or slower in order to have better performance, which the crude oil tanker are changed larger and slower to get better performance.

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There are papers about improvement of the ship performance by the representative ships but few papers about ship performance of the whole ships. The first and second, third reports showed performance data of ship, respectively, the tanker and the container, the ferry boat, which were collected since 1963 by the SEMPAKUMEISAISHO. The SEMPAKUMEISAISHO have only the ships registered in Japan. The shipbuilders in Japan have built a lot of ships and some have been sold in Japan and others to abroad. The Kanai Society of Naval Architects, Japan is collecting data of newly-built ship in the Particulars Table. It holds the ships data with more wide regions than those of the SEMPAKUMEISAISHO and some owners of ships are abroad. In this paper, the ship data were collected from the particulars table of newly built ships in the Bulletin of Kansai Society of Naval Architects, Japan. The results by collecting data show the cange of principal dimensions, sea speed, maximum continuous output of various ships. The analysis results for ship performance show that the ships, which are recently built, have better performance with the year of delivery, comparing with the results estimated by the residual resistance coefficient of the Taylor Chart.

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The effects of surface roughness on a hydrofoil performance are investigated in this paper. Model experiments using NACA2410 hydrofoil were carried out in the model basin of KUMM. The several artificial roughness were made on the hydrofoil surface by the use of paper rasps or particulate materials. Numerical calculations were also carried out combining with the 2-D boundary layer model and the 3-D lifting surface vortex lattice method. At first, a displacement thickness of boundary layer was calculated on the 2-D hydrofoil. Secondly the performance calculation was carried out on the 3-D hydrofoil of which section was considered to be canged apparently by the boundary layer displacement thickness. The calculation results are compard with the experimental results. The good results are obtained.

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In this paper a parallel neural controller for the automatic berthing will be discussed. This controller has separated hidden layer that outputs the engine and rudder respectively. A general neural network that used in berthing just has one set of hidden layer, but authors proposed parallel hidden layer. The effect of this parallel control produced good results in comparison with conventional neural controller. Furthermore many simulations conducted in this paper have different initial situations with the teaching data. In other words, starting parameters such as heading angle, ship's positions, are not same with the teaching data. But they produced successful results. Finally some simulations are conducted under slight disturbance conditions such as wind conditions and current conditions.

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A feasibility study is to done make an advancing wave system with a simple component of wavenumber on the water surface of a circulating water channel by making the wave-suppressor-plate oscillate at the top of the outlet of the channel. At first using the 2-D linearized theory for an oscillating planing plate the wave-making characteristics of the heaving and pitching motion of the suppressor are analyzed numerically. From these characteristics wave-free conditon except for only one component of advancing wave system is obtained and the calculated results under such a condition show an ability of suppressor-plate type of wave-maker for a circulating water channel. Next experimental apparatus is made to make the suppressor-plate heave(not pitch)and the generated waves are measured with two methods, image analyzing method for some instantaneous wave configurations in a period time taken by high-speed video camera and wave-height-gauge method for time sequential wave records at some positions between a half beat length. The experimental results coincides with the calculated characteristics except in the cases at lower stream velocities due to the higher ratio of wave height by length and at higher frequencies due to the lower performance of the servo type of wave gauge. From the theoretical and experimental results it is concluded that the suppressor-plate type of wave-maker can be realized when it is controlled in a given mode of combination of heaving and pitching motions.

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For an Indonesian RoRo passenger ship, the authors in their previous works had found that the annual capsizing probability calculated with the piece-wise linear approach and the existing wave statistics almost agrees with the actual capsizing rate obtained from the casualty records in Indonesia. To confirm this conclusion, in this paper the authors examine, by systematic calculations, the effect of some important input items, that is, the resolution of wave statistics, the wave duration and the roll damping. As a result, the authors confirmed that 1)the annual capsizing probability converges when the cut-off probability is 10^<-5> 2)the annual capsizing probability sightly decreases when the wave duration increases and 3)the annual capsizing probability does not significantly depend on the change in the roll damping for GM values. Therefore, the conclusion obtained in the previous works with the cut-off probability of 10^<-5> wave duration of 1200 seconds and the roll damping coefficient at the designed GM conditon can be regarded as appropriate.

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In the present paper the two-dimensional steady and unsteady problem of a hydro-planing are studied based on the linear water-wave theory. Although the usual numerical procedure is due to the boundary integral method using unknown pressure distribution on the body surface, the directmethod of the boundary element method is introduced here. The bydrodynamic problem is solved in the time-domain, where the Kutta condition at the trailing edge of a flat plate is taken into account. The wave field generated by an oscillating flat plate with a forward speed can be simulated in a wide range for a speed and an oscillating frequency by using the present method. The computed lift coefficients of a flat plate in a steady run show good results with another prediction method. The simulated wave amplitude in the unsteady wave field show the good agreements with the experimental ones. Moreover, the heave added mass and damping coefficients are computed, including the influence of the gravity. These results tend to the prediction based on the existing theory in case of the high Froude nimber, where the gravity is neglected approximately.

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Comparative calculation is carried out for investigating effects of ship form upon steady horizontal forces and moment due to short waves. Distributions of pressure of steady wave forces and some other parameters describing flow field around manoeuvring ships tell us about differences of properties of wave field between a VLCC and a container ship. Integral region defined by authors' method and that by ordinary method are compared for both ship forms. Effects of oblique angle, turning rate are also discussed in conjunction with effects of ship form. Steady wave forces and moment in shortcrested and long-crested irregular waves are calculated and effects of ship form in irregular seas are also discussed.

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The environmental impact of shipping a certain amount of cargo between Yokohama and Fukuoka by road transport and marine transport was assessed using life cycle impact assessment with some weighting factors estimated from the opinions of general consumers by analytic hierarchy process. These impacts were compared to find the environmental destruction index to show the effect of modal shifting of this amount of cargo from road to waterway. The similar impacts were also assessed by two other methods namely Eco-indicator '99 and Externalities. Then these results were compared to validate the first method(LCIA-AHP)of comparison. The economical benefit and customer service quality were also assessed and compared in this comparison process.

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This report provides results of model experiments concerning hydrodynamic forces on the rudder of a ship equipped with controllable pitch propeller(CCP). Captive model tests were performed under condition of steady straight course. In this test, rudder normal force and propeller thrust were measured by changing advance speed of a ship, CPP blade angle, and rudder angle systematically. By using these experimental results, characteristics of inflow velocity to rudder behind CPP is examined on the basis of the momentum theory for a actuator disc. Here, state of flow around rudder is classified into three regions, considering whether the momentum theory may be applied or not. The correction factor which appears in the formula of expressing the inflow velocity is assumed to be applied in the wide range of CPP blade angle. The factor, which gives added velocity due to the propeller at the rudder position, is evaluated by applying the experimental results mentioned above. As a result, it is indicated that values of the factor lie almost between 1.0 and 2.0. Moreover, it is found that generally speaking the factor gives different values for different regions of the flow states.

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The added moment of inertia about z axis of ship are very important to analyze hydrodynamic forces and also simulate maneuvering motion of ships. The added moment of inertia based on the experiments by Motora is well-known owing to its practicability for the ship design. In recent years, floating structures with C_B nearly equal 1 has been used by operation in ocean exploitaion. But Motora's charts without C_B nearly equal 1 is not enough to use for floating structures. The purpose of this paper is to present a quick chart arranged with a new parameter in order to estimate the added moment of inertia of floating structures with C_B=1. The added moment of inertia of floating structures with C_B=1 is obtained by the constant angular acceleration test and calculation of potential flow.

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The computational experiments of a ship in oblique towing motion are conducted instead of the physical model experiments in a towing tank, which are performed from rest to steady motion through constant accelerarion motion. Solving the Navier-Stokes equations for imcompressible and unsteady flows, hydrodynamic forces acting on a ship are computed with drift angles between 0 and 90 degrees. The finite volume method is used for the Navier-Stokes equation solver using the SIMPLE algorithm on colocated grids. These computational results are in good agreement with experimental results of the physical model over the whole range of drift angles in both transitional and steady states. The 3D vortex structure and pressure distribution on the ship in transitional stages in oblique towing tests can show the characteristics of the transitional hydrodynamic forces.

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A component-type mathematical model of hydrodynamic forces acting on a hull in steering motion have been developed by means of simplified vortex systems by us. This paper proposes the mathematical model modified to improve the accuracy of cross flow forces in ship's pivot turning motion. The modification of the model is supplemented by the effects of vertical bound vortices located at midship part generated by the cross flow in ship's turning motion, which compose a pair of ring vortices with horizontal bound vortices and contribute to lateral forces as the interactive forces of cross flow vortex system. The model was applied to experimental data of four model ships in the pivot rurning motion and could describe very well the experimental data.

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This paper is intended to investigate transitional characteristics of hydrodynamic forces acting on a ship hull in oblique motion from rest to steady state(drift β=0〜90 deg). The towing tests were carried out for 3 model ships of different shapes by means of small CMT apparatus. Furthermore times histories of measured forces were analyzed by a component-type mathematical model, and were transitional characteristics of viscous components were examined. The results of analysis are as follows. (1)The cross flow force component can not be dealt as the force in quasisteady state. (2)The viscous lift can be dealt approximately as the force in quasi-steady state.

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By recognizing the importance of the ship handling performance of large full vessels like VLCC for their maneuverability design, the author investigated how these vessels are operated in seaways like Malacca-Sigapore Strait, especially where restrictions in water depth and width exist, taking heavy traffics into consideration. Both the course change and the position controls are considered to be important in such restricted seaways, and the criteria for these perfomance should be determined not by the non-dimensional figures but by the dimensional figures as turning angular velocity in degree per second and overshoot path in meters. The author studied the operational circumstances, sea trial and model test results and proposed the criteria for maneuverability design of VCLL class full ships in view of ship handling performance.

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The author proposed the procedure to decide the standard rudder area required by the course stability when most of the ships adopted Inverted-G stern. After that mariner stern became popular and further these days many of the merchant ships have been built with Stern Bulb configurations. The course stability of large full ships are much affected by the difference of the stern profiles i.e. Inverted-G type, conventional Mariner type, and Stern Bulb type even if the rudder area ratios are same. The difference of the spiral loop widths due to the different stern profiles were recognized when they are plotted on the basis of the standard rudder area ratio given by the author. In addition to that, by defining the stern profile indices which is the projected skeg area ratio in stern part, the relationships between the spiral loop width and the stern profile ratio are clearly observed. The author totalized these studies and proposed a trade-off chart between the stern profile ratio and the rudder area ratio, which will give a guide to obtain the reasonably sufficient course stability in the initial design stage of maneuverability for large full ships.

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In the design process of a passenger ship, ship owners try to improve the seakeeping quality of a ship by changing ship hull shape and size, or by installing additional anti-motion apparatuses, like a fin stabilizer, an anti-rolling tank, a ride control system or an anti-pitching fin. Such improvements usually coat the ship owners. They consider the merit and the demerit of each choice carefully, and then decide which way is the best one from the point of view of operation and economics. In this paper, an evaluation method of seakeeping quality from the economical point of view is proposed. The method is divided into three parts ; prediction of ship motions in waves, prediction of vomiting ratio of MSI(Motion Sickness Incidence)of passengers on the ship, and prediction of increases of share of demand for the ship due to improvement of the vomiting ratio. The evaluation method is applied to two domestic routes in Japan.

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An experimental investigation on the transverse porpoising instability of a planning craft in drifting motion at high advance speeds in calm water is carried out. Some types of transverse porpoising are observed in measuring motions in oblique towing tests under heave, pitch and roll free condition. In order to clarify the influence of hydrodynamic forces on the transverse porpoising, captive model tests in oblique towing condition are carried out. The experiments are carried out by systematically changing trim angle, drift angle, towing speed and draft. From the measured hydrodynamic forces, the restoring forces and moments of heave, roll and pitch are calculated. The results show that the coupling restoring coefficients between heave and pitch have the different sign each other(∂F_z/∂θ>0, ∂M_y/∂z<0)and the coupling restoring coefficients between heave and roll also have the different sign each other (∂F_z/∂ψ>0, ∂M_x/∂z<0)at large drift angle. The results suggest that the transverse porpoising considering in the present paper may be a self-excited phenomena in a coupling motion among roll, pitch and heave.

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The deck wetness and the ship bottom slamming are extremely nonlinear phenomena. Traditional studies on these phenomena are experimental ones. Nowadays increase of computational resources brings availability of the particle method for these hydrodynamics problems. Then we show comparative results of the dam-break flow and the tank sloshing between numerical results with the particle method and experimental ones, which are carried out by using a video camera. In order to show the potential of the particle method for the naval architecture and ocean engineering problems, we show some calculated examples, which are interaction problems between fluid and moving body, plunging waves, and so on.

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A new wave statistics around Japan with height-period-direction correlation is composed to estimate a performance of Japanese domestic ship in actual seas. For example, the eastern sea area off the Ohshima island is selected to present the diagrams of the wave height-period-direction correlation and also speed-direction correlation of wind. The correlation between height, period and direction of waves in each season is discussed. Then it was found that the wave height-period diagram in each direction remarkably differs from the wave height-period diagram. Using the present diagrams, the effects of the wave correlation and the season on long term prediction of ship response are discussed. First, the long term prediction of ship response is carried out using two kinds of diagram. One is the present diagram of wave height-period-direction correlation, another is the diagram of wave height-period correlation, which the distribution of wave direction is assumed. It was found that the effect of wave height-period-direction correlation can not negligible from the viewpoint of ship response. Second, the long term prediction of ship response is carried out using different two kinds of diagram. One is the annual diagram, another is the diagrams in each season or month, which the annual diagram is made of. Analytically it is pointed out that the annual diagram makes a difference against the combined diagram divided by season or month. However, as a result of the long term prediction, the effect of the diagram division is small from viewpoint of ship response.

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In this paper, idealized water collision analysis is carried out in order to clarify the dominant factor which influences the water impact response of container ship bow flare. It is shown that the pressure which acts on structure is related with theoretical value _<pc>V derived from the compressibility of water. And it is also shown that deviation of the actual pressure from the theoretical value can be explained by using both the ratio of the structural vibration period to the exerting pressure period and the ratio of the structural mass to the impact water mass. Moreover, the calculation for actual container ship under water impact condition is carried out to evaluate of residual deformation of the bow structure. From the comparison of actual residual deformation and calculation result, it is shown that the maximum pressure which acts on the container ship becomes about 16-23% of theoretical value.

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Damage examples of hatch covers under green seas and bow flare subjected to slamming are reported. Studies on the phenomena and strength evaluation method have been carried out. In these phenomena, external force to cause the structure damage comes from collision between hull structure and water around it. And the structural deformation and hydrodynamic pressure are so closely related with each other that a fluid-structure dynamics interaction must be considered. However, most of these studies so far do not take the influence of the interaction into accounts. In this study, we developed a fluid-structure dynamics interaction computer program for fundamental study of these phenomena. Some calculations were carried out for collision of a 2-D flat plate with water. The effect of collision speed, stiffness of structure, and structure mass on pressure and structural deformation is discussed.

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It is an important subject to clarify the mechanism of welding crack formation to eliminate cracks in weld of real structures. Thus, the authors developed a FEM using temperature dependent interface element in order to analyze all the processes of crack formation including the generation, propagation and the arrest. The proposed method is applied to the Trans-Varestrain hot cracking test, and the influences of the parameters included in the interface element are clarified. The procedure to determine the values of the parameters is also proposed. Further, validity or the general acceptability of the parameters as material constants is demonstrated through the cross examination between the Trans-Varestrain test and the Fish Bone test. The same temperature dependent interface element is applied to the hot cracking in the transverse cross-section of laser-welded bead. The crack can formed and extend in rather arbitrary location and direction depending on the welding condition. In this report, influence of the penetration shape, the scale parameter γ_0 and BTR on the formation of the hot cracking is examined.

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In the optimization of structural design, the designer studies the obtained responses and changes the values of some design variables related to the material properties and structural dimensions in order to improve response, Response analyses are carried out repeatedly until the final design is arrived at. When such a process is adopted, however, a large number of reconstructions of the structural model are required. As a method for reducing the burden of this kind of optimization process, response surface methodology(RSM)has become widely known. By using RSM, we can reduce the number of trials of the numerical or model experiments. The authors have already applied RSM to the optimization problem of a tanker's transverse bulkhead and reported this methodology's effectiveness(Refs.1 and 2). However, because the actual structure of a ship is very complicated, the term number of the approximate polynomials used in the RSM increases rapidly if we take all the related dimensions of the structure into consideration. Therefore, even if we use RSM, the number of structural models becomes enormous, since we need many trial structural analyses to determine the parameters of the approximate polynomials. The concept of basis vectors is introduced in the present study to express structural shape with minimal information. Each basis vector shows the mode change of the shape, and by using this concept it is possible to reduce the number of design variables to a practical range. Thus the number of the necessary analyses can be sustained. In this study, we propose a method that uses the basis vectors in combination with the RSM, and we apply it to hull structural design as a means of efficient optimization. The results of a study to examine the effectiveness of this method in the optimization of a double-bottom side-bracket structure are shown.

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This paper describes a discusion on a SES concept without flexible seals. A weak point of Surface Effect Ships(SES)is considered that they have flexible seals which require both labourous maintenance treatments and high maintenance costs, Recently, a new concept of the SES without flexible seals has been reported. Its hull form consists of the twin frontal hulls and the hull with aircushions, which could eliminate the frontal and the aft flexible skirts of the usual SES. The calm water resistance was calculated and examined for this type of the hull without flexible seals. And it was compared with the resistances of the hulls with flexible seals and the usual displacement catamarans. It is found that the value of resistance of the SES without seals is about 60% of that of the usual displacement type catamarans although it is slightly higher than the SESs with flexible seals at the speed of 40〜50 knots. The results are promising the application of the hulls without flexible seals for fast carferries.

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In the present study, a new prediction method of travel demand based on society's point of view as well as users' and operators' ones is developed. In the method, firstly, prediction of travel demand from society's point of view is carried out. In the prediction, each transportation system is evaluated based on benefit and cost for society. The elements of the benefit consists of an economical impact and global time efficiency, and the cost consists of infrastructure investment by governments, global warming phenomena due to CO_2, local environmental hazard due to NO_x, and SO_x, and noise pollution. The weight of each element in society is obtained by using the Analytical Hierarchy Process model, AHP. Secondly, the economical evaluation of the obtained travel demand based on society's point of view is carried out using a generalized cost model. When these two results coincide each other, the result can be acceptable for society, users, and operators. In order to assess the present method, a feasibility study of ferries in Osaka-Takamatsu route is carried out. The results by this model show that some kinds of fast ferries are feasible to be operated to carry passengers and private cars in this route.

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The study is of an offshore structure consisting of slender columns near the free surface and large buoyancy pontoons near the base that is moored to the sea bottom like a Tension Leg Platform. The effect of the spacing between the columns of the structure on the horizontal component of the total wave force due to an irregular wave has been investigated. Since the columns are slender, diffraction of the incident wave field has been neglected and the wave force has been computed using a method proposed by Borgman for an irregular wave. This research has been done to get an insight into the design of an offshore structure that will experience low horizontal force. The sea state considered is one having a significant wave height of 6m and a mean wave period of 6s since the probability of exceedance of this sea state is low in the west coast of India where the use of this structure is contemplated.

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In January 1995, port of Kobe was severely damaged by the Hanshin-Awaji disaster. After the earthquake, almost port facilities have been recovered by the end of March 1997. Since then, various measures have been applied to achieve the most effective/efficient use of port facilities, such as reduction of handing costs, simplification of formalities and to making the Kobe port easier to use. However, container handling activities in Kobe port have not been recovered as before the disaster. In the present paper, the long-period changes of container handling activities are studies in relation with the industries, economic and social activities in Kansai area, in Japan and around the world using statistical data available. They show that the import and export activities in Kobe port have been closely related with the industries development in Kansai/West Japan area.

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In January 1995, port of Kobe was severely damaged by the Hanshin-Awaji disaster. After the earhquake, all of port facilities have been recovered by the end of March 1997. Since then, various measures have been applied to achieve the most effective/efficient use of port facilities, such as reduction of handing costs, simplification of formalities and to making the Kobe port easier to use. However, container cargo activities in Kobe port have not been recovered as that before the disaster. In the present paper, "the model of container cargo activities in Kobe port" is studied. Using the result of statistics analysis. The authors develop a model to evaluate and to estimate relations between container cargo activities and indutstrial activities of hinterland. The authors show, after numerical simulations, that the cargo activities in Kobe port have been closely related with the industry and economic activity in hinter land of Kobe port.

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The authors took part in a project for developing a new ocean model called the MEC model, the special feature of which is that the model comprises hydrostatic and full-3D(non-hydrostatic)models for analyzing two different-scale physical phenomena, i.e. 1km-100km and 1m-100m. The connection between the two models are such that the full-3D model domain matches one cell of the hydrostatic model and that the velocities of the hydrostatic model on the interface is calculated by using both of hydrostatic and full-3D velocities and those of full-3D model are interpolated trilinearly by using the ones in the hydrostatic model. We applied the model to the simulations of purification effects of the Density Current Generator set in Hazama-Inlet, Gokasyo-Bay in Mie, where red tide has been insignificant at least for these 4 years since the installation of the apparatus. Simulation results indicated that the apparatus puts the water including nutrients sucked from the bottom onto the thermocline and that such water intrudes in the horizontal direction and never mixes in the vertical direction. The water of nutrients on the thermocline is numerically simulated to spread to the whole bay within a week mainly by tidal motion.

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